Abstract In this paper, we provide a non‐Markovian Stochastic Petri Net (SPN) model for D e v O p s w o r k f l o w specification, and we determine how business processes are carried out. After describing our model semantics, we show how general properties related to liveness and safety can be checked. After that, we provide several extensions on S P N s (SPN) the notation and expressivity to check some specific properties related to actors' (Developers and Operators) availability, interactions between the actors, and execution failures detection linked to the D e v O p s steps. Next, we validate the proposed model relevance with M A T L A B simulation through a specific D e v O p s case study. Finally, we propose a truncated density function to anticipate the delays related to the D e v O p s business process overall steps.

We propose in this paper a workload-aware perform ability analysis of elastic server virtualized systems (SVS) based on non-Markovian SRN modeling approach. This analysis investigates correlations between several modules involving workload-aware power management (PM) mechanism, virtual machine (VM) and VM monitor (VMM) subject to aging, failure and rejuvenation. We show through numerical results how performance (i.e. waiting time), power usage as well as power-performance efficiency are impacted by power management attribute when using time varying workload with bursty nature. We show also how we can quantify PM attributes leading to small waiting time and a good utilization of the active power state.

Cooperative diversity or virtual antenna arrays enables transmission range extension and provides performance enhancements in wireless Multi-hop relay networks, when compared with relaying non cooperative diversity based schemes. Moreover Cooperative diversity allows better reliability to link failure and lead to a more efficient transmission that is of particular interest in mobile environment. In this paper we present a quantitative approach to analyze the steady state availability analysis of a virtual antenna array link (VMIMO) subject to failures in a multi-hop wireless network using cooperative diversity and assuming Markovian properties. We propose an end to end VMIMO availability model enabling to express performance measure such as failure frequency and failure rate. These measures quantify failure impact on VMIMO link availability. Our model generalizes availability model given in [1] and may be exploited using the same approach presented in [1] to deduce survivability performance measures such that excess loss due to failure (ELF) and excess delay due to failure (EDF).

Abstract Providing optimal resource utilization while minimizing costs involved for wireless networks remains a challenging issue. Particularly mobilead hocenvironments subject to multi‐path fading and characterized by a dynamic topology need better resource management mechanisms. The focus of this paper is the performance evaluation of IEEE 802.11e MAC layer modeling under slow time‐varying Rayleigh fading channel via both layered and multi‐layered design approaches via a non‐Markovian Stochastic Petri Nets modeling. We propose two MAC IEEE 802.11e models considering service differentiation features. The first one is non cross‐layer based, whereas the second is cross‐layer based. The cross‐layer design approach adopted permits us to deal with both collisions and fading. We show the impact of the virtual load on the expected throughput. Compared to the conventional approach, our cross‐layered design approach provides significant performance gains. Copyright © 2010 John Wiley & Sons, Ltd.

The focus of this paper is the IEEE 802.11e MAC layer modeling under slow time varying Rayleigh fading channel via both layered and multi-layered design approaches and through non Markovian Stochastic Petri Nets (NMSPN). In this paper, we carry out extensions to SPN IEEE 802.11 compact model reported in. Towards that, we investigate relaxation accounting for slow Rayleigh fading, service differentiation and cross-layer design. We propose two MAC IEEE 802.11e models including many of the EDCF extensions and accounting for slow Rayleigh fading. The first one is non cross-layer based whereas the second is cross-layer based. The cross-layer design approach adopted enables to not only manage collisions but also mitigate fading effects. We show the expected throughput behavior with respect to the virtual load at MAC level and the impact of service differentiation on MAC performance.

In this paper we present a performance study of an input/output buffered type ATM switch with backpressure mechanism with an MMPP process as input. The backpressure is exerted at the Head of Line (HOL) level to prevent output buffer cell loss. MMPP process is chosen due to its bursty nature able to capture multimedia source characteristics such as data and voice. We propose an approximate method to calculate the total waiting time in the switch. Numerical examples will be given for two states MMPP to quantitatively show the effects of output buffer size b on performance switch. The analysis is done by using structured stochastic matrices of M/G/I type and the obtained results extend those related to scalar case (Poisson process).